Remember how Utahns died as a likely result of fallout from nuclear tests in neighboring Nevada in the 1950's and early 1960's? Remember how cavalierly and callously Washington has treated repeated efforts to gain some redress for this damage?

Well, Washington now has on its hands another potential scandal involving radioactivity. And Americans had better become particularly demanding and persistent if this problem isn't to be swept under the rug, too.The latest scandal involves radon, the invisible and odorless gas produced naturally by decaying uranium. When the uranium is underground, radon can travel upwards and collect in homes and other buildings. As the gas decays, it produces particles that increase the risk of lung cancer when inhaled.

Only last month, federal officials issued a nationwide radon alert, declaring radon the nation's most serious air pollution problem and calling on all homeowners to test their homes.

So far, so good. But when it came to issuing guidelines, the government took the easy way out.

In last month's alert, Washington suggested that Americans test their homes to determine the level of radon contamination in picocuries, a common measure of radioactivity. If a home tests above four picocuries of radon per liter of air, steps should be taken to reduce it. Below that level, the guidelines indicate no need for action. And 90 percent of the nation's homes are below the 4 picocurie level.

But hold on a minute! It turns out that the level in the guidelines is anything but safe. Knight-Ridder News Service reports that people living in homes contaminated at four picocuries face the same risk of lung cancer as they would from smoking a half-pack of cigarettes a day or from receiving 200 chest X-rays a year.

That's why Rep. James J. Florio of New Jersey is sponsoring legislation that would set a national goal of reducing radon as much as possible.

How can the government justify the level it chose for the guidelines? On the grounds that it's hard for homeowners to make the kind of building changes needed to reduce radon below four picocuries. Consequently, Washington says, it didn't want to frustrate or frighten people.

Even so, the result of the guidelines is that many Americans are being lulled into a false sense of security about radon. Though it's hard to reduce radon below the level mentioned in the guidelines, some people will want to try. But they can't if they are kept in the dark. What's needed from Washington is not necessarily more laws like Rep. Florio's but more candor.